System and Method for Strain and Acceleration Based Analytics in an Independent Cart System

ABSTRACT

A system and method of monitoring forces exerted at multiple locations on a mover includes multiple sensors, where each sensor is mounted at one of the locations. Each sensor detects an operating condition of the mover at the location on the mover at which it is mounted. The sensors may include accelerometers, strain gauges, or a combination thereof. Each strain gauge is mounted proximate to an area of interest on the mover. Each strain gauge generates a feedback signal corresponding to a deformation of the material measured at the location of the sensor. From the measured deformation of material, a force acting on the mover at the location of the sensor may be determined. The forces exerted at the different locations on the mover may be monitored in real time to determine bearing performance or monitored over a duration of time to observer changes in bearing performance over that duration.

BACKGROUND INFORMATION

The subject matter disclosed herein relates to a system and method formonitoring vehicle health for an independent cart system. Morespecifically, multiple sensors, such as strain gauges and accelerometersare mounted to different locations on a vehicle to provide performanceand health of the vehicle or subsystems on the vehicle at the differentlocations.

Motion control systems utilizing independent carts and linear motors canbe used in a wide variety of processes (e.g. packaging, manufacturing,and machining) and can provide an advantage over conventional conveyorbelt systems with enhanced flexibility, extremely high-speed movement,and mechanical simplicity. The motion control system includes a set ofindependently controlled vehicles or carts, also referred to herein as“movers”, each supported on a track for motion along the track. Thetrack is made up of a number of track segments, and a linear drivesystem controls operation of the movers, causing the movers to travelalong the track. Sensors may be spaced at fixed positions along thetrack and/or on the movers to provide information about the position andspeed of the movers.

Numerous differences between different movers or differences in a singlemover over time may impact how a mover travels along the track.Variations between movers due, for example, to manufacturing tolerancesmay result in differences in physical engagement of the mover with thetrack. The variations in physical engagement may result in greaterpressure and/or friction being experienced by one of the bearings on themover than by other bearings. The bearing experiencing the greatestpressure and/or friction may wear more quickly than the other bearings.Similarly, variations in orientation of the track will result in forcesdue to gravity being exerted on the movers differently. Variations inloading on each mover as it travels along the track will cause varyingforces to be exerted on each mover. All of the variations inmanufacture, orientation, loading, and the like impact external forcesexperienced by a mover and may similarly result in greater pressureand/or friction being experienced by one of the bearings on the moverthan by other bearings.

Thus, it would be desirable to monitor forces exerted at multiplelocations on a mover.

Further, wear in bearings or rollers over time may increase variationsbetween different movers or change orientation of a single mover overtime. Wear on the track, such as a dent on a rail, or varying transitiondistances between track segments may further impact how a mover travelsalong the track.

Thus, it would be desirable to have real-time feedback corresponding tobearing performance, and to monitor changes in bearing performance overtime.

BRIEF DESCRIPTION

According to one embodiment of the invention, a system for monitoringstatus of a mover in an independent cart system includes multiplesensors, a control circuit, and a transmitter. The independent cartsystem includes multiple movers configured to travel along a track. Thesensors are mounted on the movers, and each sensor is configured togenerate at least one feedback signal corresponding to an operatingcondition of the mover. The control circuit is mounted on the mover. Thecontrol circuit is configured to receive the at least one feedbacksignal from each of the sensors and to generate a data packet includinga value corresponding to the operating condition monitored from each ofthe sensors. The transmitter is mounted on the mover. The transmitter isconfigured to receive the data packet from the control circuit and totransmit the data packet to a receiver located external from the mover.

According to another embodiment of the invention, a system formonitoring status of multiple bearings on a mover in an independent cartsystem includes multiple sensors, a control circuit, and a transmitter.The sensors are mounted on the mover, and each sensor is mountedproximate one of the bearings on the mover. Each sensor is configured togenerate at least one feedback signal corresponding to an operatingcondition of a corresponding bearing by which each of the sensors ismounted. The control circuit is mounted on the mover. The controlcircuit is configured to receive the at least one feedback signal fromeach of the sensors and to generate a data packet including a value forthe at least one feedback signal corresponding to the operatingcondition of the corresponding bearing monitored from each of thesensors. The transmitter is mounted on the mover. The transmitter isconfigured to receive the data packet from the control circuit and totransmit the data packet to a receiver located external from the mover.

According to still another embodiment of the invention, a method formonitoring status of a mover in an independent cart system includesgenerating at least one feedback signal from each of multiple sensorsmounted on the mover. The at least one feedback signal corresponds to anoperating condition of the mover and is received from each of thesensors at a control circuit mounted on the mover. The control circuitgenerates a data packet including at least one value corresponding tothe operating condition monitored by each of the sensors. The datapacket is transmitted from a transmitter mounted on the mover to areceiver located external from the mover.

These and other advantages and features of the invention will becomeapparent to those skilled in the art from the detailed description andthe accompanying drawings. It should be understood, however, that thedetailed description and accompanying drawings, while indicatingpreferred embodiments of the present invention, are given by way ofillustration and not of limitation. Many changes and modifications maybe made within the scope of the present invention without departing fromthe spirit thereof, and the invention includes all such modifications.

BRIEF DESCRIPTION OF THE DRAWINGS

Various exemplary embodiments of the subject matter disclosed herein areillustrated in the accompanying drawings in which like referencenumerals represent like parts throughout, and in which:

FIG. 1 is a perspective view of an exemplary linear cart systemincorporating multiple movers travelling along a closed curvilineartrack according to one embodiment of the present invention;

FIG. 2 is a perspective view of an exemplary linear cart systemincorporating multiple movers travelling along a closed curvilineartrack according to another embodiment of the present invention;

FIG. 3 is a partial side elevation of the linear cart system of FIG. 2 ;

FIG. 4 is a perspective view of a mover from the transport system ofFIG. 1 ;

FIG. 5 is a partial sectional view of the transport system of FIG. 1 ;

FIG. 6 is a side elevational view of a mover from the transport systemof FIG. 2 ;

FIG. 7 is a partial sectional view of the transport system of FIG. 2 ;

FIG. 8 is a partial side elevation view of one segment of one embodimentof the linear cart system of FIG. 1 illustrating activation coilsdistributed along one surface of the track segment;

FIG. 9 is an exemplary control system for a linear cart systemincorporating one embodiment of the present invention;

FIG. 10 is a block diagram representation of the control system of FIG.9 ;

FIG. 11 is a perspective view of a mover from the transport system ofFIG. 2 , illustrating multiple sensors and a control circuit mounted tothe mover according to one embodiment of the invention;

FIG. 12 is a schematic representation of an exemplary strain gaugeutilized as one of the sensors of FIG. 11 ;

FIG. 13 is a block diagram representation of an exemplary controlcircuit of FIG. 11 ;

FIG. 14 is a front elevation view of an exemplary track mounted with themajor axis of the track positioned in a vertical orientation;

FIG. 15 is a front elevation view of an exemplary track mounted in ahorizontal orientation; and

FIG. 16 is a front elevation view of an exemplary track mounted with theminor axis of the track positioned in a vertical orientation.

In describing the various embodiments of the invention which areillustrated in the drawings, specific terminology will be resorted tofor the sake of clarity. However, it is not intended that the inventionbe limited to the specific terms so selected and it is understood thateach specific term includes all technical equivalents which operate in asimilar manner to accomplish a similar purpose. For example, the word“connected,” “attached,” or terms similar thereto are often used. Theyare not limited to direct connection but include connection throughother elements where such connection is recognized as being equivalentby those skilled in the art.

DETAILED DESCRIPTION

The various features and advantageous details of the subject matterdisclosed herein are explained more fully with reference to thenon-limiting embodiments described in detail in the followingdescription. The subject matter disclosed herein describes a system andmethod of monitoring forces exerted at multiple locations on a mover.Multiple sensors are mounted on each mover at multiple locations. Eachsensor detects an operating condition of the mover at the location onthe mover at which it is mounted. According to one embodiment of theinvention, at least one accelerometer and at least one strain gauge aremounted to the mover. According to one aspect of the invention, multiplestrain gauges may be mounted to the mover, where each strain gauge ismounted proximate to one of the bearings of the mover. Each strain gaugegenerates a feedback signal corresponding to a deformation of thematerial measured at the location of the sensor. From the measureddeformation of material, a force acting on the mover at the location ofthe sensor may be determined. The strain gauges, therefore, can be usedto monitor forces exerted at multiple locations on the mover. Accordingto one aspect of the invention, the forces exerted at multiple locationson the mover may be monitored in real time to determine bearingperformance. The forces may also be monitored over a duration of time toobserver changes in bearing performance over that duration.

Each sensor is configured to generate a feedback signal corresponding tothe measured strain. It is contemplated that the feedback signals,additional processed signals, or a combination thereof may betransmitted from each mover to a remote device. Each mover travels alongthe track of the independent cart system. The remote device ispreferably a stationary device mounted external from the track and may,for example, provide a visual interface for a user on which thereal-time forces experienced at each location on the mover aredisplayed. On a smaller track, a communication bus may be mounted aroundthe track and each cart may include a brush, configured to slide alongthe communication bus and to establish a “wired” communication pathbetween the cart and the remote device. However, with branches and/or anincreased size in the track, a wired communication path becomesimpractical and a wireless communication path is preferred. Each movermay include a wireless communication device in communication with thesensors and with the remote device to transfer data directly from thesensors to the remote device. Optionally, intermediate communicationnodes may be established periodically along the track allowing awireless communication device on each mover to communicate to one of thenodes. Each node may, in turn, be connected via a wired connection, awireless connection, or a combination thereof to the remote device. Eachnode may serve as a gateway to transfer data between the carts and theremote device.

In one embodiment of the invention, it is contemplated that power foreach of the sensors and for the communication device is provided by abattery mounted on the cart. According to another embodiment of theinvention, it is contemplated that power for each of the sensors and forthe communication device is provided via a wireless power transfersystem. The wireless power transfer system may use, for example,inductive or optical coupling between a power source mounted on oradjacent to the track, where the power source is configured to emitenergy to a pickup device mounted on the cart. The pickup device isconfigured to receive the emitted energy when it is range of the powersource. Multiple power sources may be stationed around the track or,optionally, a power rail may be mounted continuously along the track anda power pick-up may be inductively coupled to the power rail tocontinuously receive power on the cart from the wireless power transfersystem. The cart may have an energy storage device in which energytransferred to the cart is stored until a sensor, control circuit, orcommunication device requires energy for activation.

Turning initially to FIGS. 1-3 , two embodiments of an exemplarytransport system for moving articles or products are illustrated. Thetransport system includes a track 10 made up of multiple segments 12,14. According to the illustrated embodiments, the segments define agenerally closed loop supporting a set of movers 100 movable along thetrack 10. The illustrated tracks 10 each include four straight segments12 with two straight segments 12 located along each side of the trackand spaced apart from the other pair. The tracks 10 also include fourcurved segments 14 where a pair of curved segments 14 is located at eachend of the track 10 to connect the pairs of straight segments 12. Thefour straight segments 12 and the four curved segments 14 form agenerally oval track and define a closed path over which each of themovers 100 may travel. It is understood that track segments of varioussizes, lengths, and shapes may be connected together to form a track 10without deviating from the scope of the invention.

In FIG. 1 , the track 10 is oriented in a horizontal plane and supportedabove the ground by a base 15 extending vertically downward from thetrack 10. The base 15 includes a pair of generally planar support plates17, located on opposite sides of the track 10, with mounting feet 19 oneach support plate 17 to secure the track 10 to a surface. In FIG. 2 ,the track 10 is shown without a base. It is contemplated that the tracks10 may be installed in different orientations, such as sloped orvertical, and include different shaped segments including, but notlimited to, straight segments, inward bends, outward bends, up slopes,down slopes and various combinations thereof. For convenience, thehorizontal orientation of the track 10 shown in FIG. 1 will be discussedherein. Terms such as upper, lower, inner, and outer will be used withrespect to the illustrated track orientation. These terms are relationalwith respect to the illustrated track and are not intended to belimiting. The movers 100 will travel along the track and take variousorientations according to the configuration of the track 10 and therelationships discussed herein may vary accordingly.

Each track segment 12, 14 includes a number of independently attachedrails 20 on which each mover 100 runs. According to the illustratedembodiments, rails 20 extend generally along the outer periphery of thetrack 10. A first rail 20 extends along an upper surface 11 of eachsegment and a second rail 20 extends along a lower surface 13 of eachsegment. It is contemplated that each rail 20 may be a singular member,which may be molded, extruded, or machined as a single rail member, oreach rail 20 may be assembled and formed from multiple members. It isalso contemplated that the cross section of the rails 20 may becircular, square, rectangular, or any other desired cross-sectionalshape without deviating from the scope of the invention. The rails 20generally conform to the curvature of the track 10 thus extending in astraight path along the straight track segments 12 and in a curved pathalong the curved track segments 14. The rails 20 may be thin withrespect to the dimensions of the track 10 and span only a partial widthof the surface of the track 10 on which it is attached.

With reference also to FIG. 5 , a first embodiment of the rail 20includes a base portion 22 mounted to the track segment and a trackportion 24 along which the mover 100 runs. Each mover 100 includescomplementary rollers 110 to engage the track portion 24 of the rail 20for movement along the track 10. Each side of the track portion 24 iswedge-shaped and each roller 110 includes a complementary grooveconfigured to receive the wedge-shaped side of the track portion.

With reference also to FIG. 7 , a second embodiment of the rail 20includes two track portions 26, 28, where a first track portion 26 and asecond track portion 28 each have a generally rectangular sectionalarea. The first track portion 26 of the upper rail 20 is positioned onthe top surface 11 of the track and first and second rollers 110 engageeach side of the first track portion 26 of the upper rail. The secondtrack portion 28 of the upper rail 20 protrudes from the side of thetrack segment orthogonally to the orientation of the first track portion26. A third roller 110 engages one surface of the second track portion28 of the upper rail. The first track portion 26 of a lower rail 20similarly has a generally rectangular sectional area and is oriented onthe lower surface 13 of the track and fourth and fifth rollers 110engage each side of the first track portion 26 of the lower rail. Thesecond track portion 28 of the lower rail 20 protrudes from the side ofthe track segment orthogonally to the orientation of the first trackportion 26, and a sixth roller 110 engages one surface of the secondtrack portion 28 of the lower rail.

One or more movers 100 are mounted to and movable along the rails 20 onthe track 10. With reference again to FIGS. 4 and 5 , a first embodimentof an exemplary mover 100 is illustrated. Each mover 100 includes a sidemember 102, a top member 104, and a bottom member 106. The side member102 extends for a height at least spanning a distance between the rail20 on the top surface 11 of the track 10 and the rail 20 on the bottomsurface 13 of the track 10 and is oriented generally parallel to a sidesurface 21 when mounted to the track 10. The top member 104 extendsgenerally orthogonal to the side member 102 at a top end of the sidemember 102 and extends across the rail 20 on the top surface 11 of thetrack 10. The top member 104 includes a first segment 103, extendingorthogonally from the side member 102 for the width of the rail 20,which is generally the same width as the side member 102. A set ofrollers 110 are mounted on the lower side of the first segment 103 andare configured to engage the track portion 24 of the rail 20 mounted tothe upper surface 11 of the track segment. According to the illustratedembodiment two pairs of rollers 110 are mounted to the lower side of thefirst segment 103 with a first pair located along a first edge of thetrack portion 24 of the rail and a second pair located along a secondedge of the track portion 24 of the rail 20. The first and second edgesand, therefore, the first and second pairs of rollers 110 are onopposite sides of the rail 20 and positively retain the mover 100 to therail 20. The bottom member 106 extends generally orthogonal to the sidemember 102 at a bottom end of the side member 102 and extends for adistance sufficient to receive a third pair of rollers 110 along thebottom of the mover 100. The third pair of rollers 110 engage an outeredge of the track portion 24 of the rail 20 mounted to the lower surface13 of the track segment. Thus, the mover 100 rides along the rails 20 onthe rollers 110 mounted to both the top member 104 and the bottom member106 of each mover 100. The top member 104 also includes a second segment120 which protrudes from the first segment 103 an additional distancebeyond the rail 20 and is configured to hold a position magnet 130.According to the illustrated embodiment, the second segment 120 of thetop member 104 includes a first portion 122 extending generally parallelto the rail 20 and tapering to a smaller width than the first segment103 of the top member 104. The second segment 120 also includes a secondportion 124 extending downward from and generally orthogonal to thefirst portion 122. The second portion 124 extends downward a distanceless than the distance to the upper surface 11 of the track segment butof sufficient distance to have the position magnet 130 mounted thereto.According to the illustrated embodiment, a position magnet 130 ismounted within a recess 126 on the second portion 124 and is configuredto align with a sensor 150 mounted within the top surface 11 of thetrack segment.

With reference again to FIG. 7 , a second embodiment of an exemplarymover 100 is illustrated. Each mover 100 includes a side member 102, atop member 104, and a bottom member 106. The side member 102 extends fora height at least spanning a distance between the rail 20 on the topsurface 11 of the track 10 and the rail 20 on the bottom surface 13 ofthe track 10 and is oriented generally parallel to a side surface 21when mounted to the track 10. The top member 104 extends generallyorthogonal to the side member 102 at a top end of the side member 102and extends across the rail 20 on the top surface 11 of the track 10. Afirst set of rollers 110 are mounted on the lower side of the top member104 and are configured to engage either side of the first track portion26 of the rail 20 mounted to the upper surface 11 of the track segment.According to the illustrated embodiment two pairs of rollers 110 aremounted to the lower side of the top member 104 with a first pairlocated along a first side of the first track portion 26 and a secondpair located along a second side of the first track portion 26 of theupper rail 20. A third pair of rollers 110 are mounted on the sidemember 102 and extend below the second track portion 28 of the upperrail. The bottom member 106 extends generally orthogonal to the sidemember 102 at a bottom end of the side member 102 and extends for adistance sufficient to receive a fourth and fifth pair of rollers 110along the bottom of the mover 100. The fourth and fifth pair of rollers110 each engage one side of the first track portion 26 of the lower rail20. A sixth pair of rollers 110 are mounted on the side member 102 andextend above the second track portion 28 of the lower rail. The rollers110 act together to engage the various surfaces of the rails 20 to bothallow the mover 100 to travel along the rails 20 and to maintain theorientation of the mover 100 with respect to the track 10. According tothe illustrated embodiment, a position magnet 130 is mounted within thetop member 104 and is configured to align with a sensor 150 mountedwithin the top surface 11 of the track segment.

With reference to both FIGS. 5 and 7 , a linear drive system isincorporated in part on each mover 100 and in part within each tracksegment 12, 14 to control motion of each mover 100 along the segment.Coils 50 (see also FIG. 8 ) mounted along the length of the track 10serve as first drive members. Each mover 100 includes a second drivemember 140 which is configured to interact with electromagnetic fieldsgenerated by the coils 50 to propel the mover 100 along the track 10. Itis contemplated that the drive members 140 on each mover 100 may bedrive magnets, steel back iron and teeth, conductors, or any othersuitable member that will interact with the electromagnetic fieldsgenerated by the coils 50. Commonly, the drive member 140 on each mover100 includes permanent magnets which emit a magnetic field. The magneticfield generated by the drive member 140 on each mover 100 improves themover interaction with the electromagnetic field generated by the coils50 in comparison to a magnetically salient structure that has nomagnetic field. For convenience, the invention will be discussed withrespect to drive magnets 140 being used as the drive member within eachmover 100. However, it is understood that the other magnetically salientstructures may be employed without deviating from the scope of theinvention.

With reference to FIG. 8 , a series of coils 50 are positioned along thelength of the track 10. Each mover 100 includes at least one drivemagnet 140 configured to interact with an electromagnetic fieldgenerated in the coils. Successive activation of the coils 50establishes a moving electromagnetic field that interacts with themagnetic field generated by each permanent magnet 140 mounted on themovers 100 and that causes the mover 100 to travel along the track 10.Controlled voltages are applied to each coil 50 to achieve desiredoperation of the movers. The drive magnets 140 are mounted on the innersurface of the side member 102 and when mounted to the track 10 arespaced apart from a series of coils 50 extending along the track 10. Asshown in FIGS. 5 and 7 , an air gap 141 is provided between each set ofdrive magnets 140 and the coils 50 along the track 10. According to theillustrated embodiment, each coil 50 is placed in a channel 23 extendinglongitudinally along one surface of the track segment 12. Theelectromagnetic field generated by each coil 50 spans the air gap 141and interacts with the drive magnets 140 mounted to the mover 100 tocontrol operation of the mover 100.

Turning next to FIG. 9 , a portion of another exemplary independent carttransport system for moving articles or products is illustrated. Theillustrated system includes a track 310 made up of multiple segments312. Rather than traveling along the sides of the track, as shown inFIG. 1 , the illustrated movers 100 travel along a channel in the track310. The channel is defined by a bottom surface 316 and a pair ofopposing side walls 313. Rails 314 are placed along the length of theupper surface of each side wall 313 and are configured to support andengage the mover 100 as it travels along the track 310. Power isdelivered to segments 312 via a DC bus 320 extending along the track310. The DC bus 320 includes a positive rail 322 and a negative rail 324where any suitable voltage potential is provided between the positiveand negative rails to energize the coils 50.

The portion of the system illustrated in FIG. 9 includes two straightsegments 312 and further illustrates an exemplary control systemconnected to the independent cart transport system. A segment controller51 is provided within each track segment 312 to regulate current flow tothe coils 50 forming the portion of the linear drive system in eachtrack segment 312. Optionally, each segment controller 51 may also beresponsible for all, or a portion of, the motion control of each mover100 as it travels along the corresponding segment 312. According to oneembodiment of the invention, the segment controllers 51 may be mountedtogether in a control cabinet. A cable, multiple cables, separateconductors, or a combination thereof extend from the control cabinet toeach segment 12, 14 to deliver current to the coils 50 and to receivefeedback signals, for example, from position sensors 150. In smallersystems, each segment controller 51 and an industrial controller 200 maybe included in a single control cabinet. Depending on the size andlayout of the track 10, additional control cabinets may be distributedaround the track and a portion of the segment controllers 51 located ina control cabinet proximate the track segment 12, 14 they control.Separate control cabinets and controllers within a cabinet arecommunicatively connected via the network medium 160. Althoughillustrated as blocks in FIG. 9 external to the track segments 312, theillustration is to facilitate illustration of interconnects betweencontrollers. According to still another embodiment, it is contemplatedthat each segment controller 51 may be mounted in the lower portion 319of the track segment 312. Each segment controller 51 is in communicationwith an adjacent segment controller 51 and a central controller 170which is, in turn, in communication with an industrial controller 200.According to yet another embodiment, the central controller 170 may beremoved and the functions of the central controller 170 incorporatedinto the segment controllers 51, the industrial controller 200, or acombination thereof, and each segment controller 51 may communicatedirectly with the industrial controller 200.

The industrial controller 200 may be, for example, a programmable logiccontroller (PLC) configured to control elements of a process linestationed along the track 10. The process line may be configured, forexample, to fill and label boxes, bottles, or other containers loadedonto or held by the movers 100 as the travel along the line. In otherembodiments, robotic assembly stations may perform various assemblyand/or machining tasks on workpieces carried along by the movers 100.The exemplary industrial controller 200 includes: a power supply 202with a power cable 204 connected, for example, to a utility powersupply; a communication module 206 connected by a network medium 160 tothe other controllers 51, 170; a processor module 208; an input module210 receiving input signals 211 from sensors or other devices along theprocess line; and an output module 212 transmitting control signals 213to controlled devices, actuators, and the like along the process line.The processor module 208 may identify when a mover 100 is required at aparticular location and may monitor sensors, such as proximity sensors,position switches, or the like to verify that the mover 100 is at adesired location. The processor module 208 transmits the desiredlocations of each mover 100 to a central controller 170 or to therespective segment controllers 51 where the receiving controlleroperates to generate commands for the current required in each coil 50of the corresponding segment controller 51 to control motion of eachmover 100. Optionally, the industrial controller 200 may include amodule in one of the slots of the chassis or embedded as a routineexecuting within the processor module 208 to perform a portion of thecommand generation and the processor module 208 may transmit a currentcommand to a segment controller rather than a desired location.

With reference also to FIG. 10 , each module in the industrialcontroller 200 may include its own memory and processor and beconfigured to execute one or more routines corresponding to the desiredoperation of the respective module. The portion of the industrialcontroller illustrated in FIG. 10 , shows a first processor 207 and afirst memory device 209 located in the processor module 208 and a secondprocessor 203 and a second memory 205 located in the communicationmodule 206. A backplane connects each module within the industrialcontroller 200 and backplane connectors 201 a, 201 b are shownconnecting the two modules. Although illustrated as directly connectingthe two modules, the backplane is a communication bus extending alongthe chassis of the industrial controller and each backplane connector201 for a module engages a complementary backplane connector on thecommunication bus aligned with the slot on the chassis in which themodule is inserted. A communication interface 199 within thecommunication module 206 is configured to connect to the industrialnetwork 160.

The central controller 170 includes a processor 174 and a memory device172. It is contemplated that the processor 174 and memory device 172 mayeach be a single electronic device or formed from multiple devices. Theprocessor may be a microprocessor. Optionally, the processor 174 and/orthe memory device 172 may be integrated on a field programmable array(FPGA) or an application specific integrated circuit (ASIC). The memorydevice 172 may include volatile memory, non-volatile memory, or acombination thereof. An optional user interface 176 may be provided foran operator to configure the central controller 170 and to load orconfigure desired motion profiles for the movers 100 on the centralcontroller 170. Optionally, the configuration may be performed via aremote device connected via a network and a communication interface 178to the central controller 170. It is contemplated that the centralcontroller 170 and user interface 176 may be a single device, such as alaptop, notebook, tablet or other mobile computing device. Optionally,the user interface 176 may include one or more separate devices such asa keyboard, mouse, display, touchscreen, interface port, removablestorage medium or medium reader and the like for receiving informationfrom and displaying information to a user. Optionally, the centralcontroller 170 and user interface may be an industrial computer mountedwithin a control cabinet and configured to withstand harsh operatingenvironments. It is contemplated that still other combinations ofcomputing devices and peripherals as would be understood in the art maybe utilized or incorporated into the central controller 170 and userinterface 176 without deviating from the scope of the invention.

The central controller 170 includes one or more programs stored in thememory device 172 for execution by the processor 174. The centralcontroller 170 can receive instructions for coordinating with industrialprocesses or machines. In one aspect, known as “centralized” control,the central controller 170 can determine one or more motion profiles forthe movers 100 to follow along the track 10. A program executing on theprocessor 174 is in communication with each segment controller 51 oneach track segment via a network medium 160. The central controller 170may transfer a command signal to the segment controller 51 in each tracksegment to control energization of the coils 50. The central controller170 may receive feedback signals corresponding to the identificationand/or location of movers 100 along each track segment and controlmotion of the movers 100 directly from the central controller 170. Inone embodiment of the invention, it is contemplated that the centralcontroller 170 may be implemented within the industrial controller 200as either a portion of the control program executing in the processormodule 208 or as a dedicated motion control module inserted within oneof the slots of the industrial controller 200.

In another aspect, known as “distributed” control, the centralcontroller 170 may be configured to transfer the desired motioncommands, or a portion thereof, from the central controller 170 to eachof the segment controllers 51. The motion commands identify one or moredesired movers 100 to be positioned at or moved along each track segment312. The central controller 170 may distribute motion commands to eachsegment controller 51 according to the mover 100 located at or proximateto the track segment 312. The corresponding segment controller 51 foreach track segment 312 may, in turn, determine the appropriate commandsignals for each mover 100 and transmit the command signals to one ormore power segments in each track segment to control energization of thecoils 50. Distributed control can minimize the amount of communicationin the system by allowing segment controllers 51, rather than thecentral controller 170, to control driving each mover 100 along thetrack 310. In one embodiment of the invention, it is contemplated thatthe central controller 170 may be implemented within the industrialcontroller 200 as either a portion of the control program executing inthe processor module 208 or as a dedicated motion control moduleinserted within one of the slots of the industrial controller 200.

A position feedback system provides knowledge of the location of eachmover 100 along the length of the track segment 12, 14 to the segmentcontroller 51. In one embodiment, the position feedback system caninclude one or more position magnets 130 mounted to the mover 100 and anarray of sensors 150 spaced along the track segment 12, 14. Withreference again to FIG. 1 , for convenience, only a few position sensors150 are illustrated along one track segment 12. It is contemplated thatthe position sensors 150 would continue along each track segment 12, 14and for the entire length of the track 10. The sensors 150 arepositioned such that each of the position magnets 130 are proximate tothe sensor as the mover 100 passes each sensor 150. The sensors 150 area suitable magnetic field detector including, for example, a Hall Effectsensor, a magneto-diode, an anisotropic magnetoresistive (AMR) device, agiant magnetoresistive (GMR) device, a tunnel magnetoresistance (TMR)device, fluxgate sensor, or other microelectromechanical (MEMS) deviceconfigured to generate an electrical signal corresponding to thepresence of a magnetic field. The magnetic field sensor 150 outputs afeedback signal provided to the segment controller 51 for thecorresponding track segment 12 on which the sensor 150 is mounted. Thefeedback signal may be an analog signal provided to a feedback circuit58 which, in turn, provides a signal to the processor 52 whichcorresponds to the magnet 130 passing the sensor 150.

The segment controller 51 also includes a communication interface 56that receives communications from the central controller 170, fromadjacent segment controllers 51 in a path, and the industrial controller200. The communication interface 56 extracts data from the messagepackets on the communication network and passes the data to a processor52 executing in the segment controller 51. The processor may be amicroprocessor. Optionally, the processor 52 and/or a memory device 54within the segment controller 51 may be integrated on a fieldprogrammable array (FPGA) or an application specific integrated circuit(ASIC). It is contemplated that the processor 52 and memory device 54may each be a single electronic device or formed from multiple devices.The memory device 54 may include volatile memory, non-volatile memory,or a combination thereof. The segment controller 51 receives the motionprofile or desired motion of the movers 100 and utilizes the motioncommands to control movers 100 along the track segment 312 controlled bythat segment controller 51.

Each segment controller 51 generates switching signals to generate adesired current and/or voltage at each coil 50 in the track segment 312to achieve the desired motion of the movers 100. The switching signals72 control operation of switching devices 74 for the segment controller51. According to the illustrated embodiment, the segment controller 51includes a dedicated gate driver module 70 which receives commandsignals from the processor 52, such as a desired voltage and/or currentto be generated in each coil 50 and generates switching signals 72.Optionally, the processor 52 may incorporate the functions of the gatedriver module 70 and directly generate the switching signals 72. Theswitching signals 72 are provided to the power conversion segment ineach track segment 312, where each power conversion segment includesmultiple power switching devices 74. The switching devices 74 may be asolid-state device that is activated by the switching signal, including,but not limited to, transistors, thyristors, or silicon-controlledrectifiers.

In one embodiment, the processor 52 can also receive feedback signalsfrom sensors providing an indication of the current operating conditionswithin the power segment or of the current operating conditions of acoil 50 connected to the power segment. According to the illustratedembodiment, the power segment includes a voltage sensor 62 and a currentsensor 60 at the input of the power segment. The voltage sensor 62generates a voltage feedback signal and the current sensor 60 generatesa current feedback signal, where each feedback signal corresponds to theoperating conditions on the positive rail 322. The segment controller 51also receives feedback signals corresponding to the operation of coils50 connected to the power segment. A voltage sensor 153 and a currentsensor 151 are connected in series with the coils 50 at each output ofthe power section. The voltage sensor 153 generates a voltage feedbacksignal and the current sensor 151 generates a current feedback signal,where each feedback signal corresponds to the operating condition of thecorresponding coil 50. The processor 52 executes a program stored on thememory device 54 to regulate the current and/or voltage supplied to eachcoil and the processor 52 and/or gate driver 70 generate switchingsignals 72 which selectively enable/disable each of the switchingdevices 74 to achieve the desired current and/or voltage in each coil50. The energized coils 50 create an electromagnetic field thatinteracts with the drive magnets 140 on each mover 100 to control motionof the movers 100 along the track segment 12.

Turning next to FIG. 11 , multiple sensors 360 may be mounted to eachmover 100 to monitor status of the mover during operation. According tothe illustrated embodiment, each sensor 360 is mounted proximate to oneof the rollers 110 for the mover 100. The sensor 360 is configured togenerate a feedback signal 365 corresponding to a force applied to therespective roller 110 by which it is mounted. The sensor 360 may be, forexample, an accelerometer, a gyroscope, or a strain gauge. A forceapplied to the mover 100 via the linear drive system will generate anacceleration or deceleration of the mover measurable by theaccelerometer. The forces experienced by mover 100 as it travels, forexample, from the linear drive system, from friction along the rails, orfrom a load applied to the mover 100 may cause some rotational motion ofthe mover 100 measurable by the gyroscope and typically provided as aroll, pitch, and yaw of the mover. The force applied to the mover 100via the linear drive system may cause some deflection (either expansionor contraction) of the material from which the mover 100 is constructedat the location at which the sensor 360 is mounted and which ismeasurable by the strain gauge. Thus, providing sensors at theselocations generates a feedback signal corresponding to a force appliedto the mover as seen at the location of the sensor.

As also illustrated in FIG. 11 , it is contemplated that one or morecoordinate systems may be defined for the independent cart system. Afirst coordinate system 420 may be a primary reference coordinatesystem, having a first x-axis, X, a first y-axis, Y, and a first z-axis,Z. This primary reference coordinate system may be used by all deviceswithin the independent cart system or alternate coordinate systems maybe utilized according to the application requirements. Each mover 100,for example, may have a mover coordinate system 425 assigned to themover. An origin for the mover coordinate system 425 is located at adesired position with respect to the mover, and a second x-axis, X_(m),a second y-axis, Y_(m), and a second z-axis, Z_(m), are defined withrespect to the origin of the mover coordinate system 425. Further, eachsensor 360 may have a sensor coordinate system 430 defined with respectto the location at which the sensor is located. An origin for the sensorcoordinate system 430 is located where the sensor is mounted and, asillustrated, may be at the center of each sensor. A third x-axis, X_(s),a third y-axis Y_(s), and a third z-axis, Z_(s), are defined withrespect to the origin of the sensor coordinate system 430. The feedbacksignals 365 generated by each sensor may be assigned to one of thecoordinate systems and translated between coordinate systems accordingto defined offsets between origins of the coordinate systems.

As previously indicated, the sensor 360, according to one aspect of theinvention, may be a strain gauge 400. With reference also to FIG. 12 ,an exemplary circuit for the sensor 360 as a strain gauge 400 isillustrated. The illustrated embodiment is an electrical strain gaugeconstructed from a wheatstone bridge 405 having four resistors. Oneresistor is a variable resistor, where the resistance changes as afunction of the strain present at the location. A conductive trace 404applied to a foil material 402 is mounted over the location of interest.If strain causes a deformation in the location of interest, the foil 402mounted on the location is either elongated or compressed as a result ofthe deformation. The elongation or compression of the foil 402 causes asimilar change to the conductive trace 404 mounted on the foil 402.Elongation and compression of the conductive trace 404 will alter thelength and width of the conductive trace 404 thereby varying theresistance along the length of the trace 404. A voltage applied acrossthe variable resistance is provided to an amplifier 410, which, in turn,generates the feedback signal 365, corresponding to the strain presenton the location. A varying resistance in the strain gauge 400 will causea varying output voltage, V_(out), corresponding to the varyingresistance, to the measured strain, and to force applied at thelocation.

With reference again to FIG. 11 , each sensor 360 generates a feedbacksignal 365 provided to a control circuit 370 mounted on the mover 100.An enclosure may be provided around the control circuit 370 to protectthe control circuit from contamination in a manufacturing environment.With reference also to FIG. 13 , the control circuit 370 includes aninterface 385 to receive each of the feedback signals 365. It iscontemplated that the interface 385 may include analog-to-digital (A/D)converters, amplifiers, buffers, multiplexers, and the like to convertvoltage signals output from each sensor 360 to a digital value.Optionally, each sensor 360 may be configured to transmit data in aserial bit stream or as part of a data packet. The interface 385 mayinclude a complementary communication interface to receive the digitaldata and provide the data values to a controller 375.

The controller 375 is configured to assemble the data received from eachsensor into a data packet for transmission from the mover 100. Thecontroller 375 may be a microcontroller, a microprocessor, a fieldprogrammable gate array (FPGA), application specific integrated circuit(ASIC), or the like. It is contemplated that the controller 375 isconfigured to execute a series of instructions stored in memory, wherethe memory is either on board the controller or is an external device.The controller 375 may be configured to assemble the data directly intoa data packet for transmission according to a desired communicationprotocol. Optionally, the controller 375 may be configured to performsome initial processing, for example, converting a measured strain to aforce, as discussed below. The controller 375 may then assemble theprocessed data into a data packet for transmission according to thedesired communication protocol.

The data packet is provided to a transmitter 390 and antenna 395 mountedon the mover to transmit the data from the sensor 360 to a controllerlocated remotely from the mover 100. One or more receivers 350 (see alsoFIGS. 9-10 ), may be positioned along the track 10. In someapplications, a single receiver 350 may have sufficient range andbandwidth to communicate with each mover 100 traveling along the track10. In other applications, the number of movers 100 may generate avolume of data packets that exceed the bandwidth of a single receiver350 or the distance of travel along the track 10 may exceed the range ofthe receiver. As illustrated in FIG. 9 , each segment controller 51 mayinclude or have a receiver 350 connected to the segment controller 51.The transmitter 390 transmits data packets containing either themeasured value from the feedback signal or a processed data value,corresponding to the measured value, to a receiver 350 of the segmentcontroller 51 in closest proximity to the mover 100. The receiver 350,in turn, transmits the data to the segment controller 51 or to a centralcontroller 170 or industrial controller 200 in communication with thesegment controller 51.

The control circuit 370 also includes a power circuit 380 mounted on themover 100. The power circuit 380 is configured to supply power to thesensor 360, controller 375, and transmitter 390. According to oneembodiment of the invention, the power circuit 380 may include a batteryconfigured to supply power. One or more voltage regulators receive powerfrom the battery and supply a regulated DC voltage, for example, at 3.3VDC, 5 VDC, 12 VDC, 24 VDC, any other required DC or AC voltage, or acombination thereof. Optionally, the mover 100 includes a pickup deviceconfigured to travel along with the mover and to receive powertransmitted from a power source external to the mover. The power sourcemay be, for example, a supply coil or supply rail which receives acurrent that generates an electromagnetic field. The pickup device maybe a coil mounted on the mover in which a secondary current is inducedas the mover travels through the electromagnetic field. The secondarycurrent is supplied to a voltage regulator circuit to provide therequired voltages to each of the devices on the mover or to an energystorage device to store excess energy not required by the devices. Ifmore power is required than may be provided from the pick-up device,energy stored in the energy storage device may supplement the energysupplied from the pick-up coil.

The feedback signals 365 are transmitted to a controller located remotefrom the mover 100. The controller may be the segment controller 51controlling the section of track on which the mover is located.Optionally, the controller may be the central controller 170 for theindependent cart system or the industrial controller 200 controllingoperation of the track and external actuators. It is furthercontemplated that a dedicated receiver 350 or multiple receivers may bepositioned around the track 10 to receive the feedback signals 365 fromeach mover 100 and the dedicated receiver 350 may relay the informationto one of the controllers. The feedback signals may be utilized tomonitor bearing wear and/or predict remaining life of bearings at eachroller 110 on a mover.

In operation, the force applied to the mover 100 and operatingconditions of the mover are monitored at multiple locations by sensors360 mounted at each location on the mover. Each sensor 360 mounted onthe mover 100 generates one or more feedback signals 365 correspondingto a force applied to the mover 100. It is contemplated that each sensor360 may be a single axis sensor, generating a feedback signal 365corresponding to one of the axes of the sensor coordinate system 430 oreach sensor 360 may be a multiple axis sensor, generating feedbacksignals 365 corresponding to two or all three axes of the sensorcoordinate system 430.

According to one embodiment of the invention, the sensor 360 is a straingauge 400 configured to monitor deflection of the mover 100 at thelocation on which the strain gauge is mounted. The feedback signal 365corresponding to the strain measured by the sensor may be used todetermine the force experienced by the mover 100 at the location of thesensor. With equation 1, the measured strain may first by converted to astress experienced by the mover 100. Young's Modulus is a materialproperty of the mover 100 and is a known value based on the constructionof the mover. The value of Young's Modulus for each mover 100 may bestored in memory of one of the controllers and used to convert themeasured strain to the value of stress.

σ_(n) =Eε _(n)  (1)

where:σ_(n) is the stress determined at sensor “n”,ε_(n) is the strain measured at sensor “n”, andE is Young's Modulus for the material at the location of sensor “n”.

After determining the stress with equation 1, the stress may beconverted to a force experienced by the mover at the sensor location byusing equation 2. The value of stress previously determined ismultiplied by the sectional area of the mover at the location of thesensor to determine a force observed at the location of the sensor.

$\begin{matrix}{\sigma_{n} = \frac{F_{n}}{A}} & (2)\end{matrix}$

where:σ_(n) is the stress determined at sensor “n”,F_(n) is the force observed at the location of sensor “n”, andA is the sectional area of the mover at the location of section “n”.

Having determined a force present at each bearing, a controller may beused to monitor real-time performance of a mover 100 or to trackperformance of the mover over time. According to one aspect of theinvention, it is contemplated that the controller monitoring performancemay be the segment controller 51 monitoring performance of each mover100 as the mover 100 travels along the segment controller 51. Thesegment controller 51 monitors the forces in real-time and may generatea warning or fault message to be transmitted to either the centralcontroller 170 or the industrial controller 200 if a force exceeds apredetermined threshold. Optionally, the segment controller 51 may storevalue of the forces observed for each mover in the memory 54 for thesegment controller. An initial value may be stored during commissioningand changes in the value over time may be monitored. When a differencein the measured value of force (observed under consistent operatingconditions) exceeds a predefined threshold, the segment controller 51may generate a warning or fault message to be transmitted to either thecentral controller 170 or the industrial controller 200.

According to another aspect of the invention, the controller monitoringperformance may be the central controller 170 or the industrialcontroller 200. If the receivers 350 are connected to each segmentcontroller 51, the segment controllers 51 may be configured toretransmit data packets containing data from the sensors 360 to eitherthe central controller 170 or the industrial controller 200. Optionally,the receivers 350 may be connected directly to the central controller170 or the industrial controller 200 and the corresponding controllermay receive data from the sensors 360 directly from each mover 100. Thecentral controller 170 or industrial controller 200 may be configured tostore data from each of the multiple movers 100 in the independent cartsystem. The controller may monitor the data in real-time or over aduration of time in a manner similar to that discussed above for eachsegment controller.

The controller configured to monitor performance of the movers 100 inthe independent cart system may detect a number of different operatingconditions based on the feedback signals from the sensors 360. Accordingto a first aspect of the invention, the controller may be configured todetermine a misalignment between adjacent track segments 12. As eachmover 100 transitions between a first track segment 12, 14 and a secondtrack segment 12, 14, where the second track segment is adjacent to thefirst track segment, there should be little or no change in operatingperformance between track segments. Ideally, each track segment ismanufactured identical to one another and there is no change inoperating performance as a mover transitions between track segments.However, variations do exist between adjacent track segments due tomanufacturing tolerances, assembly tolerances, and the like. In someinstances, adjacent track segments 12, 14 may have some misalignmentbetween the two segments. A mover 100 will experience a spike in strainand acceleration as it transitions between the misaligned segments. Ifthe value of the spike in strain and/or acceleration exceeds apredefined threshold, the controller may generate a warning or faultmessage alerting a technician to the misalignment between adjacent tracksegments.

According to another aspect of the invention, the controller may beconfigured to determine remaining life of bearings on each roller 110.Each roller 110 may include a ball bearing, roller bearing, or othersuitable bearing according to application requirements. The controllermay be configured to monitor values detected by strain gauges 400 todetermine forces applied to the bearings and further provide anindication of remaining bearing life. With reference to FIGS. 14-16 ,orientation of the track 10 may impact bearing life. With reference alsoto FIGS. 6 and 11 , it may be observed that rollers 110 engage differentportions 26, 28 of the rails 20 with different orientations. Acombination of the orientation of each roller 110 on the mover 100 andthe orientation of the track 10 will cause different rollers 110 toexperience greater forces from gravity, g, than other rollers. With thetrack mounted in a vertical orientation, as shown in FIGS. 14 and 16 ,the rollers 110 oriented horizontally in FIG. 6 will experience agreater force due to gravity, g, than the rollers 110 orientedvertically in the same figure. With the track mounted in a horizontalorientation, shown in FIG. 15 , the rollers 110 oriented vertically inFIG. 6 and positioned on the lower portion of the mover 100 will engagean upper surface of the portion 28 of the rail 20 protruding from thetrack segment and experience the greatest force due to gravity, g.Without the application of any other force, the bearings on rollers 110experiencing greater forces due to gravity will wear quicker than thebearings on other rollers 110. Measurements of the strain observed onthe mover by each roller 110 provide an indication of the forceexperienced by each roller 110 and, in turn, by the bearings on eachroller.

The controller may monitor the status of the rollers 110 observing thegreatest forces and determine the remaining life of each roller and/orthe bearing on each roller. In addition to forces generated by gravity,forces will be exerted on the mover 100 due to acceleration and loadingof the mover 100. The memory of the controller may include a look uptable corresponding to expected life of a bearing as a result of variousforces applied. The controller may maintain a record of the operation ofeach mover 100 and the forces measured to determine a remaining life ofeach bearing. When the remaining life drops below a first threshold, awarning message may be generated to alert a technician preventivemaintenance is required. If the remaining life drops below a secondthreshold, a second warning message or a fault message may be generatedindicating an imminent failure of the bearing and roller 110 ispossible.

According to another aspect of the invention, the orientation of thetrack may be determined by monitoring the feedback signals 365 from eachsensor 360. When the mover is stationary, a force due to gravity willgenerate a reading from an accelerometer corresponding to a negativenine and eight-tenths meters per second square (−9.8 m/s²) in thedirection of gravity. If a multi-axis accelerometer is mounted on themover 100, the controller may determine orientation of the track 10based on the axis along which the accelerometer is detecting the −9.8m/s² reading.

According to still another aspect of the invention, the feedback signals365 from the sensors 360 may be utilized to determine the presence of apayload on the mover 100. With reference again to FIG. 11 , theillustrated mover 100 includes an opening 101 on the upper surface ofthe mover 100. It is contemplated that the opening 101 has a threadedinterior surface, and a fixture (not shown) may be secured to theopening 101 with a bolt, screw, or other threaded fastener. The fixturemay be a platform on which a load may be set. Optionally, the fixturemay include a gripper, vacuum member, clamp, or other such grippingmember to secure a load on the mover 100. The weight of a payloadmounted on the mover 100 will exert a downward force on the top member104 of the mover and a torque on the bolts 105 securing the top member104 to the side member 102. The force may cause deflection on the topmember 104 and/or side member 102 and, in particular near the edges ofeach member where the top and side members are joined. A strain gaugemounted proximate each roller 110 along the top of the side member 102or at the rollers 110 along the inward side of the top member 104 willdetect the deflection due to the presence of a load on the mover 100.Further, a greater load will cause a greater deflection. The controller(segment controller 51, central controller 170, or industrial controller200) configured to receive the feedback signal 365 from the strain gauge400 may utilize a look-up table or execute a calculation to determine aweight of the payload as a function of the additional strain measuredwhen loaded. Thus, each strain gauge may be used not only to detect thepresence of a load on each mover, but further be utilized to determinethe amount of loading present on the mover 100.

It is yet another aspect of the invention, the feedback signals 365 maybe utilized to monitor wear in the independent cart system. Duringcommissioning or during early operation of the mover 100, a first valueof the feedback signal 365 may be stored during a particular operation.For example, as the mover 100 travels across a particular location, thestrain, stress, or acceleration may be monitored and stored in memory.Optionally, multiple values of the feedback signal 365 may be stored asthe mover 100 travels along a length of the track. During subsequentoperation of the mover 100, measured values of strain, stress, oracceleration, as observed in the feedback signals 365 may be compared tothe stored values. A change in the feedback value over time that exceedsa predefined threshold may indicate excessive wear or damage that hasoccurred to the mover 100 or to the track segment 12, 14 over which themover 100 is travelling. A warning or fault message may be generated toalert a technician to the change in value and to the mover 100 and/or tothe track segment 12, 14 on which the change in value in occurred,providing an indication of the wear or damage in the independent cartsystem.

Still another aspect of the invention allows a controller to determineimprovements to a motion profiled being executed by the mover 100. Asdiscussed above, each mover 100 is controlled by the linear drive systemto travel along the track. The industrial controller 200, centralcontroller 170, segment controller 51, or a combination thereof isoperational to generate a motion profile for each mover. The segmentcontroller 51 controls operation of the coils 50 spaced along the trackto achieve the desired motion of each mover 100. As a mover 100 travelsalong the track 10, the feedback signals 365 from each sensor 360 may beperiodically stored to obtain a corresponding measured accelerationprofile, velocity profile, stress profile, or strain profilecorresponding to the motion profile generated by the controller. One ofthe controllers analyzes the feedback signals 365 stored in memory toidentify the greatest value of the acceleration, velocity, stress, orstrain. This maximum value of the measured feedback may be compared to afirst predefined threshold. Optionally, the controller may analyze thefeedback signals 365 to identify a duration of time along the profileduring which the values exceed a second predefined threshold. When themeasured performance of the mover 100 exceeds an instantaneous maximumvalue or when the measured performance of the mover 100 exceeds a secondmaximum value for a predefined duration, the controller may generate amessage alerting a technician to the performance. Optionally, thecontroller may be further configured to adapt the motion profile beinggenerated to reduce the maximum value or to reduce the sustained valueover the duration, thereby reducing the overall stress or strain on thesystem.

It should be understood that the invention is not limited in itsapplication to the details of construction and arrangements of thecomponents set forth herein. The invention is capable of otherembodiments and of being practiced or carried out in various ways.Variations and modifications of the foregoing are within the scope ofthe present invention. It also being understood that the inventiondisclosed and defined herein extends to all alternative combinations oftwo or more of the individual features mentioned or evident from thetext and/or drawings. All of these different combinations constitutevarious alternative aspects of the present invention. The embodimentsdescribed herein explain the best modes known for practicing theinvention and will enable others skilled in the art to utilize theinvention.

In the preceding specification, various embodiments have been describedwith reference to the accompanying drawings. It will, however, beevident that various modifications and changes may be made thereto, andadditional embodiments may be implemented, without departing from thebroader scope of the invention as set forth in the claims that follow.The specification and drawings are accordingly to be regarded in anillustrative rather than restrictive sense.

We claim:
 1. A system for monitoring status of a mover in an independentcart system, wherein the independent cart system includes a plurality ofmovers configured to travel along a track, the system comprising: aplurality of sensors mounted on the mover, wherein each of the pluralityof sensors is configured to generate at least one feedback signalcorresponding to an operating condition of the mover; a control circuitmounted on the mover, wherein the control circuit is configured toreceive the at least one feedback signal from each of the plurality ofsensors and to generate a data packet including a value corresponding tothe operating condition monitored from each of the plurality of sensors;and a transmitter mounted on the mover, wherein the transmitter isconfigured to receive the data packet from the control circuit and totransmit the data packet to a receiver located external from the mover.2. The system of claim 1 wherein at least one of the plurality ofsensors is a strain gauge and at least one of the plurality of sensorsis an accelerometer.
 3. The system of claim 1 wherein each of theplurality of sensors is a strain gauge.
 4. The system of claim 3wherein: the mover includes a plurality of bearings; each of theplurality of sensors is mounted proximate one of the plurality ofbearings; and the at least one feedback signal corresponds to a forcepresent on a corresponding bearing by which each of the plurality ofsensors is mounted.
 5. The system of claim 4 further comprising acontroller configured to receive the at least one feedback signal fromeach of the plurality of sensors and to determine a remaining life forthe corresponding bearing by which each of the plurality of sensors ismounted.
 6. The system of claim 1 further comprising: a battery mountedon the mover, wherein the battery is configured to provide power foreach of the plurality of sensors, the control circuit, and thetransmitter; and at least one voltage regulator circuit mounted on themover and configured to transfer power from the battery to each of theplurality of sensors, the control circuit, and the transmitter.
 7. Thesystem of claim 1 further comprising: at least one power pickup devicemounted on the mover, wherein the power pickup device is configured totravel with the mover and to receive power transmitted from a stationarypower source mounted along a track of the independent cart system; andat least one voltage regulator circuit mounted on the mover andconfigured to transfer power from the at least one power pickup deviceto each of the plurality of sensors, the control circuit, and thetransmitter.
 8. The system of claim 1 wherein the operating conditioncorresponding to the at least one feedback signal is selected from oneof: a misalignment between a first segment of the track and a secondsegment of the track, the second segment positioned adjacent to thefirst segment; a remaining life of a bearing for at least one rollermounted on the mover; an orientation of the track; a presence of apayload on the mover; a determination of wear on either the mover or thetrack; and a motion profile of the mover.
 9. A system for monitoringstatus of a plurality of bearings on a mover in an independent cartsystem, the system comprising: a plurality of sensors mounted on themover, wherein each of the plurality of sensors is mounted proximate oneof the plurality of bearings on the mover and each of the plurality ofsensors is configured to generate at least one feedback signalcorresponding to an operating condition of a corresponding bearing bywhich each of the plurality of sensors is mounted; a control circuitmounted on the mover, wherein the control circuit is configured toreceive the at least one feedback signal from each of the plurality ofsensors and to generate a data packet including a value for the at leastone feedback signal corresponding to the operating condition of thecorresponding bearing monitored from each of the plurality of sensors;and a transmitter mounted on the mover, wherein the transmitter isconfigured to receive the data packet from the control circuit and totransmit the data packet to a receiver located external from the mover.10. The system of claim 9 wherein at least one of the plurality ofsensors is a strain gauge and at least one of the plurality of sensorsis an accelerometer.
 11. The system of claim 9 wherein each of theplurality of sensors is a strain gauge.
 12. The system of claim 11,wherein the at least one feedback signal corresponds to a force presenton the corresponding bearing by which each of the plurality of sensorsis mounted.
 13. The system of claim 12 further comprising a controllerconfigured to receive the at least one feedback signal from each of theplurality of sensors and to determine a remaining life for thecorresponding bearing by which each of the plurality of sensors ismounted.
 14. The system of claim 9 further comprising: a battery mountedon the mover, wherein the battery is configured to provide power foreach of the plurality of sensors, the control circuit, and thetransmitter; and at least one voltage regulator circuit mounted on themover and configured to transfer power from the battery to each of theplurality of sensors, the control circuit, and the transmitter.
 15. Thesystem of claim 9 further comprising: at least one power pickup devicemounted on the mover, wherein the at least one power pickup device isconfigured to travel with the mover and to receive power transmittedfrom a stationary power source mounted along a track of the independentcart system; and at least one voltage regulator circuit mounted on themover and configured to transfer power from the power pickup device toeach of the plurality of sensors, the control circuit, and thetransmitter.
 16. A method for monitoring status of a mover in anindependent cart system, the method comprising the steps of: generatingat least one feedback signal from each of a plurality of sensors mountedon the mover, wherein the at least one feedback signal corresponds to anoperating condition of the mover; receiving the at least one feedbacksignal from each of the plurality of sensors at a control circuitmounted on the mover; generating a data packet with the control circuit,wherein the data packet includes at least one value corresponding to theoperating condition monitored by each of the plurality of sensors; andtransmitting the data packet from a transmitter mounted on the mover toa receiver located external from the mover.
 17. The method of claim 16further comprising the step of receiving the data packet at a controllerlocated remotely from the mover.
 18. The method of claim 16 wherein eachof the plurality of sensors is a strain gauge.
 19. The method of claim18 wherein: each mover includes a plurality of bearings; each of theplurality of sensors is mounted proximate one of the plurality ofbearings; and the at least one feedback signal corresponds to a forcepresent on a corresponding bearing by which each of the plurality ofsensors is mounted.
 20. The system of claim 19 further comprising thestep of determining a remaining life with the controller for thecorresponding bearing by which each of the plurality of strain gauges ismounted.